The present invention is directed to the field of improvements in pallets for securing electronic circuit boards during the manufacturing process.
Circuit board manufacturing is well known in the art. Electrical components (i.e. processors, memory, capacitors, diodes, resistors, and the like) are generally added to a blank circuit board to create a board which is later installed in an electrical device such as a computer. The blank circuit board must be held in place during the manufacturing process. This is usually accomplished through the use of a circuit board pallet.
There are many different patents directed towards methods of securing the circuit board to the pallet. The most common method is to use a plurality of pins extending upwardly from the pallet which fit into holes on the circuit board. The pallet typically has adjustment arms that create either a tensile or compressive force between these pins to hold the circuit board in place. The most common method of attaching the pins to the pallet is to drill a hole either partially through the pallet from the top or completely through the pallet and wedge a portion of the pin into the hole. These two pin attachment methods are illustrated in FIG. 1A and 1B. This configuration leaves a portion of the pin methods are illustrated in FIG. 1A and 1B. This configuration leaves a portion of the pin protruding from the top surface of the pallet so that the circuit board can be attached to the pallet. If the pin is too high, it will interfere with the various component positioning and soldering devices which pass over the circuit board during the manufacturing process. If the pin is too low, it will not sufficiently hold the circuit board in place. Therefore, the distance the pin protrudes from the pallet is an important consideration in the manufacturing process and as a result, the tolerances for pin height are very tight. Furthermore, this pin height must remain within these tight tolerances throughout thousands of cycles of heating and cooling. If the pin height falls out of the tolerance range, then the pallet must be discarded and replaced with a new pallet.
Once the circuit board has been affixed to the pallet, the components may be added to the circuit board, typically by soldering. In order for the components to be soldered in place, they must be properly positioned over the circuit board using a component support structure. The components must be held in place sufficiently long for the solder process to be completed and for the solder to cool and harden. Once the solder has cooled and hardened, it securely affixes the component to the circuit board and the component support structure may be removed from the components.
The frequent and repetitious soldering and other manufacturing processes subject the pallet to intense heat, often in excess of 550xc2x0 F. Because the pallet is made from a non-conductive material (i.e. fiberglass) and the pins are metal, the pallet and the pin expand and contract at different rates. The differing rates of contraction and expansion eventually cause the pin to move out of the tolerance range. Therefore, a need exists for a method of installing a pin into a pallet such that it will not fall out of tolerance range after repeated heating and cooling.
Moreover, although there have been a myriad of different devices proposed to position the components in place, the previous solutions to this problem have been bulky, complicated, and/or cumbersome to operate. Virtually all of the previous solutions are specific to a certain type of component and/or a certain configuration of components on the board. The prior art does not contain a device that is adaptable to a plurality of different component types and configurations on the circuit board. Consequently, a need also exists for an apparatus and method for efficiently positioning components over a circuit board during the soldering process that is adaptable to a variety of different components. Furthermore, a need exists for a component positioning apparatus that is robust enough to be adaptable to a plurality of different component sizes, shapes, and configurations on the circuit board.
The present invention, which meets the needs stated above, is a circuit board pallet with an improved circuit board retention pin and component positioning arms. The improved pin of the present invention is cylindrical in shape with an enlarged head. A countersunk hole is drilled in the bottom of the pallet to accommodate the pin. The pin is inserted into the countersunk hole and secured with a high-temperature epoxy resin. The epoxy holds the pin securely in place and keeps the pin from moving up or down.
The present invention also comprises at least one arm. The arm is affixed at one end to a swivel joint. The swivel joint allows the arm to rotate about a vertical axis. The upper portion of the swivel joint is hinged such that the arm can rotate about a horizontal axis. The combination of movement about the horizontal and vertical axis allows the arm to be positioned at any point over the pallet, and consequently, the circuit board.
In the manufacturing process, the blank circuit board is secured to the pallet using the securement pins. Next, the arm is positioned away from the circuit board and the components are secured to the arm. The arm is then positioned over the circuit board and secured to the anchor. Finally, the components may be soldered to the circuit board. Additional components may be secured to the arm and installed on the circuit board as needed.